2017-12-11 22:31 GMT+01:00 Guy Harris <g...@alum.mit.edu>: > On Dec 5, 2017, at 4:47 AM, Bruno Verstuyft <bruno.verstu...@gmail.com> > wrote: > > > 2017-12-04 22:21 GMT+01:00 Guy Harris <g...@alum.mit.edu>: > > > >> On Nov 16, 2017, at 1:21 AM, Bruno Verstuyft <bruno.verstu...@gmail.com > > > >> wrote: > >> > >>> we put the specification of the XRA header online. > >> > >> The MAC document speaks of "logical" upstream and downstream channels; > are > >> those what the "Downstream Channel ID" and "Upstream Channel ID" TLVs > refer > >> to? > >> > > Yes, from the MULPI spec: > > Logical (Upstream) Channel: A MAC entity identified by a unique channel > ID > > and for which bandwidth is allocated by an > > associated MAP message. A physical upstream channel may support multiple > > logical upstream > > channels. The associated UCD and MAP messages completely describe the > > logical channel. > > You might want to say "ID of downstream *logical* channel" in the remarks > for "Downstream Channel ID"; the remarks for "Upstream Channel ID" already > say "logical upstream channel" (is it best to say "logical XXX channel" or > "XXX logical channel"?). >
In the DOCSIS specs, there is no occurence of the term downstream logical channel, since there are only physical downstream channels. In the upstream, a physical upstream channel (channel around a center frequency) can be divided into multiple logical channels. This division is time based. More information can be found in 5.2.1.1.3.1 "Downstream Data Forwarding in a MAC Domain" and 5.2.1.1.3.2 " Upstream Data Forwarding in a MAC Domain" in the DOCSIS MULPI spec. It is best to say logical upstream channel, since this is the term used in the DOCSIS specs. > > >> To what do the start and stop minislots in the "Minislot ID" TLV refer? > > > > These are the minislots, relative in an OFDMA frame. The minislot with > the > > lowest subcarriers has id 0. > > So those are the minislots from section 7.4.1 "Signal Processing > Requirements" of the PHY specification? > Yes, updated in the Xra Header spec. > > >> What do the "Symbol ID", "Burst ID", and "Subplot ID" TLVs contain? > > > > Symbol ID is a number assigned to each symbol by our hardware. This is > > mainly used for timing calculations. It can also be used to visualize the > > correlation between NCP (Next Codeword Pointers) and the corresponding > > downstream data packets. > > So to which symbol in the packet does that refer? > The first symbol of the packet. Updated in the spec. > > > Burst ID is used to map mac frames to the corresponding databurst. A > > databurst can e.g. contain a segment:(see MULPI 7.2.4 > > Continuous Concatenation and Fragmentation). This means a segment can > > contain multiple Mac frames, or a Mac frame can be spread over multiple > > segments. In our sniffer, we extract these Mac frames from the segments. > To > > save the information of which Mac frame belongs to which segment (or > > multiple segments), we use the Burst ID: each data burst gets a unique > > Burst ID. In the Mac Frame the "Burst Info"/"Burst ID reference" is used > to > > reference these Burst IDs. > > So your sniffer assigns the Burst IDs? > > There's a variable-length "Burst ID" field and a "Burst ID Reference" > field. Does the "Burst ID" field contain a single burst ID? If so, to > which burst was that ID assigned? And what does the "Burst ID Reference" > field contain? > > Added extra explanation in the spec. > >> Does the SID TLV contain the Service Identifier for the service flow in > >> which the packet was sent? > > > > Yes > > You might want to spell out "Service Identifier" in the remarks. > Updated in spec. > > >> Does the IUC TLV contain the Interval Usage Code for the burst if the > >> packet is a burst? > > > > Yes > You might want to spell out "Interval Usage Code" in the remarks. > > Updated in spec _______________________________________________ tcpdump-workers mailing list tcpdump-workers@lists.tcpdump.org https://lists.sandelman.ca/mailman/listinfo/tcpdump-workers
